1. Field of the Invention
The present invention relates to a system for controlling devices and for distributing information, and more particularly, to a system used in home automation for controlling various devices, such as lights, HVAC, security, and audio/video devices.
2. Discussion of the Related Art
As more and more products become available that are controlled by microprocessors and computerized systems, there is an increasing need to interconnect these devices and to control and coordinate their operation.
For example, a modem home may contain a security system consisting of an alarm, security cameras, and motion detectors; entertainment devices such as VCRs, TVs, audio amplifiers, speaker distribution systems, and remote control devices; communications devices such as corded and cordless telephones, answering machines, and caller id devices; electronic lighting and heating controls; and many other electronic and electromechanical devices. There is a great need to control and partially automate the use of these devices in a way that is simple, consistent, and convenient for the user.
Similarly, in a multimedia classroom, museum exhibit, or conference room there may be a need to control lighting, motorized window drapes, multiple VCRs, video projectors, and sound systems, as well as to distribute audio and video signals among multiple sources and destinations.
Many of the devices involved in such systems have several common characteristics:
a) It is generally possible to control the devices via either a simple communications port provided as part of the device (such as an IR remote control input of a VCR, an RS-232 port on a laser disk player, a keypad input of a security panel or a low-voltage relay input of a drapery controller) or via an external device (such as a computer-controllable lighting dimmer panel). PA1 b) The aggregate bandwidth needed to control even a large number of devices is very low. A few bytes of data are generally sufficient to change the state of any such device. PA1 c) The interfaces to these devices are generally quite simple but highly variable from device to device; the variability is due to lack of standardization. PA1 a) Attempts to define universal standards for the external interfaces for these devices. These standards generally have taken the form of distributed control networks (such as Echelon's LONWorks, CEBus, or SmartHouse). However, the universal adoption of any such standard is questionable, and in any event is a long way off. PA1 b) The creation of products that combine the ability to control many such devices in a single package. For example, home-automation devices are available that can send and receive IR remote control commands, control home heating and security devices, and interface to lighting controllers. Although these devices are often somewhat modular, they are characterized by a limited set of pre-defined interface options, and typically have a fixed set of "slots" reserved for optional I/O boards. This has the disadvantages of requiring consumers to purchase functionality that they may not require and the interface may not be readily extensible to new or unanticipated requirements. PA1 c) Distributed multimedia control systems, such as the AMX Axcess system. These systems are characterized by proprietary low-bandwidth control networks combined with special-purpose devices for each control function (such as relay boxes and lighting controllers). This approach tends to be expensive because each special-purpose control device is custom engineered and has its own packaging, power supply, and interface requirements. In addition, these devices are typically pure control networks and are not readily extensible to the distributed control and access to other media types, such as voice and video. PA1 a. A common, customizable form and a standardized shell made of plastic or other material suitable for containing a diversity of simple electronic products. PA1 b. The ability to "stack" any number of such devices such that they can all communicate with each other and with a host computer or control system through a single communications port. PA1 c. Standardized protocols for communicating among devices and between devices and external computing devices. These protocols are optimized for low cost and maximum flexibility rather than on maximum performance. PA1 d. A multi-channel audio-video communications bus, permitting the interchange of multimedia data among devices. PA1 e. Control modules capable of automating the operation of multiple devices without the intervention of an external computing device. PA1 f. Interface modules capable of providing I/O capability to collections of modules, allowing users to interact with such collections, forming "custom appliances" unanticipated by the manufacturer of the modules.
It is often difficult or impossible to control large numbers of devices from a centralized device, such as a personal computer. The difficulty is due to the large number of I/O ports necessary, ports which are often in short supply on typical personal computers.
Previous efforts at providing coordinated control for such devices have generally taken one of three approaches:
Another concern is the great expense involved in bringing even a very simple new technology product to a manufacturable state. As integrated circuits become more powerful, more flexible, smaller, and less expensive an increasing percentage of the total costs of many new products are incurred, not in providing the basic functionality of the product, but rather in ancillary matters. Often the entire function of a simple electronic device can be realized in a single off-the-shelf micro controller chip costing just cents per unit. To bring such a product to market, however, may require hundreds of thousands of dollars in tooling, mechanical engineering, package design, development of interface and control protocols. Such expenses often render otherwise viable niche products economically infeasible. There is a need to address this problem by developing a standard platform on which a variety of inter-operable electronic devices can be built, without incurring the prohibitive engineering costs.
The variety of specific combinations of functions and features required to satisfy the widely varied requirements of users is growing more rapidly than the ability of the market to supply such combinations. Furthermore, in an effort to meet widely varied requirements, manufacturers have been forced to add more and more specific features to each product. This has led to increased complexity and cost of products, and users have been forced to purchase complex, feature-laden products even if their need is for only a small subset of the features included in a package.
Previous workers have been deterred from making these improvements because virtually all attention in the area of communications architectures has been directed at the high-end of the market; concentrating on higher and higher communications bandwidth and highly general large scale networking schemes. The value of applying simpler, mature technologies to fill a large collection of lower-end needs in a very general way has not generally been recognized.
Moreover, at present it is difficult to augment other hardware devices with additional capability not originally built into the device. For example, in interactive video applications the set-top-box device supplied by the service provider may have only a limited amount of memory, display, or I/O capability. The memory limitation also limits the range of software applications that can be offered by the provider. For instance, an electronic mail application may require external non-volatile memory to store incoming mail messages; a home shopping application may require a credit-card reader to be attached to the device; and an enhanced telephony service might require the attachment of a cordless phone and caller-ID functions.